1. Field of the Invention
The present invention relates to a laser level, and particularly to a side by side laser level capable of level indication along multi directions in a circumferential area simultaneously.
2. Description of Related Art
In the construction industry, drawing or determining a distant horizontal or vertical line from a reference line is sometimes not easy to achieve in one step, especially for those desired lines located at different walls. Conventional methods for carrying out the line-drawing or line-determination operation can be performed by utilizing rulers, ink-string boxes, levelers, and so on as are well well-known in the art. However, these conventional methods may be tedious and difficult to achieve accurately, and may be subject to human error.
Subsequently, a variety of survey tools employing lasers have been developed to determine level horizontal or plumb vertical planes for construction, surveying, remodeling, etc. For example, U.S. Pat. Nos. 3,771,876, 3,897,637, 4,333,242, 4,852,265, 4,904,081 and 4,912,851 illustrate various apparatuses utilizing laser technology for the construction industry. These and other similar devices utilize lasers to assist in leveling, aligning, plumbing or surveying operations.
U.S. Pat. No. 3,771,876 is directed to a laser apparatus for producing a plane or conical optical reference surface. The device includes a pendulum hanging from a flexible suspending member, with the pendulum containing the light source so as to be self-leveling. A prism device is used for reflecting the beam out of the device 90 degrees from the entry angle of the beam from the pendulum. The prism device is mounted on a vertical axle which can be caused to be rotate by a motor, whereby a conical reference surface is produced. However, the rotation of the prism device is easy to cause the laser apparatus to shake, thereby adversely affecting the accuracy of the laser apparatus. Further, since a motor is employed to drive the prism device to rotate, the volume of the laser apparatus is inevitably increased and the manufacturing cost is also increased.
In U.S. Pat. No. 3,897,637, there is disclosed a level tool utilizing a helium-neon laser for projecting a beam both vertically and horizontally. The device is not self-leveling and required manual leveling. It is rather large and required connection to an external source of power.
In some applications, when there is a need to provide level indication along various directions in a circumferential area, multi level indications are conducted time after time. Obviously, it is time-consuming.
Hence, an improved laser lever is required to overcome the disadvantages of the related art.